Component carrier for a dosing system

ABSTRACT

A component carrier of a dosing system including a plurality of components for injecting a urea solution into the exhaust gas flow of an internal combustion engine comprises a base plate forming the component carrier, a plurality of inner flow channels integrated into the base plate, and an inlet port and an outlet port connecting the inner flow channels with the coolant circuit of the internal combustion engine. The component carrier is heated by flowing a fluid having an elevated temperature and circulating in the coolant circuit from the inlet port to the outlet port passing through the inner flow channels and transferring the heat from the fluid to the component carrier. The components of the dosing system mounted on the component carrier and in thermal contact with the component carrier are heated by heat transfer from the heated component carrier.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application is based on is a continuation-in-part ofU.S. patent application Ser. No. 13/128,491, filed on May 10, 2011,which claims the 371 benefit of priority of PCT/EP2009/006389 Sep. 3,2009, the entireties of which are hereby incorporated by reference.

The invention relates to a component carrier of a dosing system forinjecting a urea solution into the exhaust gas flow of an internalcombustion engine for selective catalytic reduction, the dosing systembeing connected/connectable to a urea tank from which urea solution canbe taken, and the dosing system being connected/connectable to acompressed air supply, the dosing system having a pump for deliveringthe urea solution and the dosing system having at least one nozzlethrough which the urea solution can be injected into the exhaust gasflow by means of compressed air.

So-called SCR catalytic converters are used to reduce the nitrogen oxideemission of diesel engines. For this purpose a reducing agent isinjected into the exhaust gas system with a dosing device. Ammonia isused as the reducing agent.

Since the carrying of ammonia in motor vehicles is a safety issue, ureais used in aqueous solution with conventionally 32.5% urea proportion,especially according to DIN 70070. In the exhaust gas the ureadecomposes at temperatures above 150° Celsius into gaseous ammonia andCO₂. The parameters for the decomposition of the urea are essentiallytime (vaporization and reaction time), temperature and the droplet sizeof the injected urea solution. In these SCR catalytic convertersselective catalytic reduction (SCR) reduces the emission of nitrogenoxides by roughly 90%. The urea solution used according to DIN 70070 isalso labeled so-called AdBlue.

The urea solution is dosed by means of a dosing system, injected intothe exhaust gas flow and provides for the desired chemical reaction inthe SCR catalytic converter. In this connection the nitrogen oxides areconverted into nitrogen and water vapor.

The urea solution freezes at −11° C. In order to ensure operation of thedosing system for injection of a urea solution such as AdBlue into theexhaust gas even below this temperature, the system components must beheated. Electrical resistance elements are used for this purpose.

The disadvantage here is that electrical energy is needed for heating.Furthermore it is disadvantageous that the dosing system becomes verycomplex and expensive since a host of different components must beheated with a correspondingly large number of electrical heatingelements.

The object of the invention is to make available a dosing system inwhich heating of the system components is possible and at the same timethe system-engineering cost is reduced and the dosing system has asimple structure.

This object is achieved as claimed in the invention by a componentcarrier for a dosing system as claimed in claim 1, by a dosing systemfor injection of a urea solution as claimed in claim 12 and by anarrangement as claimed in claim 13. Advantageous configurations of theinvention are given in the dependent claims.

In the component carrier of a dosing system for injection of a ureasolution into the exhaust gas flow of an internal combustion engine forselective catalytic reduction, the dosing system beingconnected/connectable to a urea tank from which the urea solution can betaken, and the dosing system being connected/connectable to a compressedair supply, the dosing system having a pump for delivering the ureasolution and the dosing system having at least one nozzle through whichthe urea solution can be injected into the exhaust gas flow by means ofcompressed air, it is especially advantageous that the components of thedosing system are mounted/can be mounted in thermal contact with thecomponent carrier on the component carrier and the component carrier hasat least one contact region for producing thermal contact with a fluidwith a higher temperature, especially with the coolant circuit of theinternal combustion engine so that the component carrier forms/can forma heat sink and is heated/can be heated so that the components which aremounted/can be mounted on the component carrier are heated/can beheated.

The components of the dosing system which are mounted/can be mounted onthe component carrier can be the pump and/or a urea solution line and/ora compressed air line and/or valves such as control valve(s) and/ornonreturn valve(s) and/or ports.

In the dosing system for injection of a urea solution into the exhaustgas flow of an internal combustion engine for selective catalyticreduction, the dosing system being connected/connectable to a urea tankfrom which urea solution can be taken, and the dosing system beingconnected/connectable to a compressed air supply, the dosing systemhaving a pump for delivering the urea solution and the dosing systemhaving at least one nozzle through which the urea solution can beinjected into the exhaust gas flow by means of compressed air, it isespecially advantageous that the dosing system has a component carrieras claimed in the invention and components of the dosing system,especially the pump and/or a urea solution line and/or a compressed airline and/or valves and/or ports are mounted in thermal contact with thecomponent carrier on the component carrier, the component carrier beingin thermal contact with a coolant circuit of the internal combustionengine.

In the arrangement of a component carrier of a dosing system forinjection of a urea solution into the exhaust gas flow of an internalcombustion engine for selective catalytic reduction, the dosing systembeing connected to a urea tank from which urea solution can be taken,and the dosing system being connected to a compressed air supply, thedosing system having a pump for delivering the urea solution and thedosing system having at least one nozzle through which the urea solutioncan be injected into the exhaust gas flow by means of compressed air, itis especially advantageous that components of the dosing system,especially the pump and/or a urea solution line and/or a compressed airline and/or valves and/or ports are mounted in thermal contact with thecomponent carrier on the latter, the component carrier being thermallyin contact with a coolant circuit of the internal combustion engine andforming a heat sink of the coolant circuit.

Thermal contact here means that a heat-conducting contact is formedwhich enables heat transfer. The component carrier is thus incorporatedinto the coolant circuit of the internal combustion engine in terms ofheat engineering so that exhaust heat of the internal combustion engineis transferred via its coolant to the component carrier and via thecomponent carrier to different components of the dosing system so thatthese components are heated by means of the exhaust heat of the internalcombustion engine. The component carrier thus forms a heat sink in thecoolant circuit of the internal combustion engine.

That components can be mounted/are mounted on the component carrier doesnot mean by limitation that they are arranged in a certain positionrelative to the component carrier, for example vertically above thecomponent carrier, but rather that the components are mounted/can bemounted in any position relative to the component carrier on the latterand heat transfer from the component carrier to the components or viceversa is possible. It is thus also possible to transfer the exhaust heatof the delivery pump via the component carrier to other components.

In this way, an arrangement and the heating of the components of adosing system for injecting a urea solution into the exhaust gas flow ofan internal combustion engine for selective catalytic reduction on acommon base plate are easily possible, in particular premounting on thedosing system can take place so that it can be mounted as a completemodule, mounted on the component carrier.

Preferably the contact region of the component carrier is formed by atleast one recess and/or receiver into which a line which heats thecomponent carrier is inserted/can be inserted, the line carrying a fluidwith elevated temperature so that the component carrier can form/forms aheat sink.

Preferably the component carrier has several grooves and/or receiverswhich are located on the outside and into which lines are inserted/canbe inserted which carry a fluid with elevated temperature.

Especially preferably the line/lines are coolant lines and/or coolanthoses of the internal combustion engine. Heating of the components ofthe dosing system thus takes place preferably via coolant hoses whichhave been clipped in. In this way the exhaust heat of the internalcombustion engine can be easily and advantageously used to heat thecomponents of the dosing system. Alternatively or cumulatively the useof exhaust heat from system components such as pump or proportionalcontrol valve is also possible by heat transfer via the componentcarrier in order to heat the parts and components which carry the ureasolution.

Especially preferably the component carrier consists of a metal or analloy which has good heat conduction properties, especially aluminum oran aluminum alloy, and/or the component carrier is formed from a baseplate, especially a plastic plate, which has a heat-conducting coating,especially is jacketed by an aluminum sheet.

The component carrier is preferably formed by a metal plate which has alengthwise extension, the groove/grooves and/or receiver/receiversrunning along the plate so that a large contact region is formed. Theheat transfer to the components to be heated can be optimized by acorresponding choice of a material with good heat conduction propertiesfor the component carrier and an advantageous geometrical configurationof the contact region/regions.

Especially preferably the component carrier has a high coefficient ofheat transfer at least in the region of the contact regions, especiallyof the groove/grooves and/or receiver/receivers. Preferably thecomponent carrier has high thermal conductivity at least in the regionof the contact regions, especially of the groove/grooves and/orreceiver/receivers. In this way the heat transfer to the componentcarrier can be facilitated and optimized.

To improve heat transfer, additives such as contact gel or the like canbe introduced into the contact region. Preferably the lines areclipped/can be clipped into grooves and/or receivers. This facilitatesmounting and insertion of the lines for forming a heat-conductiveconnection between the lines and the component carrier.

Especially preferably the component carrier has mounting elements,especially dovetail-shaped elements, by means of which it can be mountedin the corresponding receivers, especially mounting elements of adamping material, especially rubber.

According to the advantageous embodiments of the present invention, acomponent carrier of a dosing system including a plurality of componentsfor injecting a urea solution into the exhaust gas flow of an internalcombustion engine including a coolant circuit for selective catalyticreduction, comprises a base plate forming the component carrier, aplurality of inner flow channels integrated into the base plate, and aninlet port and an outlet port connecting the inner flow channels withthe coolant circuit of the internal combustion engine. The componentcarrier is heated by flowing a fluid having an elevated temperature andcirculating in the coolant circuit from the inlet port to the outletport passing through the inner flow channels and transferring the heatfrom the fluid to the component carrier. The components of the dosingsystem mounted on the component carrier and in thermal contact with thecomponent carrier are heated by heat transfer from the heated componentcarrier.

By integrating the inner flow channels of the component carrier into thecooling circuit of the internal combustion engine, all componentsmounted on the component carrier will be heated automatically and evenlythrough heat transfer by contact. No heat conducting jacket for thecomponent carrier or separate heating elements are needed in accordancewith this embodiment of the invention. This simplifies maintenanceprocedures by making the components mounted on the component carriereasier accessible. By mounting the components of the dosing system onthe component carrier and by heating those components through thecomponent carrier by transferring heat from the engine coolant systemvia the component carrier to those components an advantage is reachedover the known prior art by eliminating the need to surround thecomponents of the dosing system with a housing, such as a box, and toheat the interior of the housing utilizing heating elements.

According to preferred embodiments of the present invention, thecomponents of the dosing system mounted on the component carrier includea pump, an air valve, a nonreturn valve, a urea solution line, acompressed air line, at least one nozzle, and ports to the urea solutionline, the compressed air line and the at least one nozzle.

According to preferred embodiments of the present invention, thecomponent carrier forms a heat sink within the coolant circuit of theinternal combustion engine.

According to preferred embodiments of the present invention, the baseplate is made of a metal, alloy, or plastic material having good heatconducting properties.

According to preferred embodiments of the present invention, the baseplate is a solid plate.

According to preferred embodiments of the present invention, the fluidis engine coolant.

According to preferred embodiments of the present invention, the innerflow channels are designed such that heat from the fluid is transferredto the component carrier.

According to preferred embodiments of the present invention, the innerflow channels are arranged in parallel.

According to preferred embodiments of the present invention, the innerflow channels are positioned at the top, the bottom or on either side ofthe component carrier.

According to preferred embodiments of the present invention, thecomponents mounted on the component carrier are heated automaticallythrough heat transfer by contact.

According to preferred embodiments of the present invention, the dosingsystem is connected to a urea tank from which urea solution can betaken, and wherein the dosing system is further connected to acompressed air supply.

According to preferred embodiments of the present invention, the dosingsystem includes a pump for delivering the urea solution and at least onenozzle through which the urea solution is injected into a exhaust gasflow of the internal combustion engine by means of compressed air.

According to preferred embodiments of the present invention, thecomponent carrier has mounting elements of a vibration-damping material,and wherein the mounting elements are used to connect the componentcarrier with the urea tank.

According to preferred embodiments of the present invention, thecomponents of the dosing system are pre-assembled to the componentcarrier prior to the installation of the component carrier in the ureatank.

According to the advantageous embodiments of the present invention, adosing system for injecting a urea solution into the exhaust gas flow ofan internal combustion engine including a coolant circuit for selectivecatalytic reduction is disclosed. The dosing system comprises a ureasolution line that connects the dosing system with a urea tank, acompressed air line that connects the dosing system to a compressed airsupply, a pump for retrieving the urea solution from the urea tank, atleast one nozzle through which the urea solution can be injected intothe exhaust gas flow utilizing compressed air from the compressed airsupply, an air valve positioned in the compressed air line, a nonreturnvalve positioned downstream of the pump, and a component carrierincluding a plurality of inner flow channels and an inlet port and anoutlet port connecting the inner flow channels with the coolant circuitof the internal combustion engine. The urea solution line, thecompressed air line, the pump, the at least one nozzle, the air valveand the nonreturn valve are mounted on the component carrier and inthermal contact with the component carrier.

According to preferred embodiments of the present invention, thecomponent carrier is heated by flowing a fluid having an elevatedtemperature and circulating in the coolant circuit from the inlet portto the outlet port passing through the inner flow channels andtransferring the heat from the fluid to the component carrier.

According to preferred embodiments of the present invention, the ureasolution line, the compressed air line, the pump, the at least onenozzle, the air valve and the nonreturn valve are heated by heattransfer from the heated component carrier.

According to preferred embodiments of the present invention, the amountof compressed air, which is supplied for atomization of the ureasolution, is controlled at each operating point depending on theoperating parameters exhaust gas temperature and exhaust gas flow and isreduced to the minimum amount of air which is required at the time sothat the droplet quality of the injected urea solution is sufficient forthe action of the catalytic converter.

According to preferred embodiments of the present invention, the airvalve is a proportional control valve enabling exact control of theamount of air that is supplied for injection of the urea solution intothe exhaust gas flow.

According to the advantageous embodiments of the present invention, amethod for controlling the injection of urea solution into the exhaustgas flow of an internal combustion engine including a coolant circuitfor selective catalytic reduction is disclosed. The method comprises thesteps of: connecting a component carrier including a plurality of innerflow channels and an inlet port and an outlet port connecting the innerflow channels with the coolant circuit of the internal combustionengine, mounting a plurality of components of a dosing system on thecomponent carrier and in contact with the component carrier, wherein thecomponents of the dosing system include an urea solution line, acompressed air line, a pump, at least one nozzle, an air valve and anonreturn valve, heating the component carrier by flowing a fluid, whichhas an elevated temperature and circulates in the coolant circuit, fromthe inlet port to the outlet port thereby passing through the inner flowchannels and transferring the heat from the fluid to the componentcarrier, heating the plurality of components of the dosing system byheat transfer from the heated component carrier, and forming with thecomponent carrier a heat sink within the coolant circuit of the internalcombustion engine.

In this way simple and prompt mounting of the component carrier or ofthe pre-mounted module consisting of the component carrier and thecomponents mounted thereon is possible when the dosing system is beinginstalled. Preferably the dosing system is located on the urea solutiontank. For this purpose the urea tank has corresponding dovetail groovesinto which the dovetail elements of the component carrier are inserted.Preferably the mounting elements which are located on the componentcarrier consist of a vibration-damping material such as rubber or thelike so that vibrations are not transferred so that decoupling of thepump and tank is enabled.

In the systems currently being used in motor vehicles compressed air andurea are combined in a mixing chamber and injected into the exhaust gasvia a single perforated nozzle. The air mass flow is set here to aconstant value in order to prevent backflow of the urea into the airflow upstream of the mixing chamber. In this way a defined boundarybetween urea-carrying regions and urea-free regions is constituted andurea crystal formation in the mixing system is avoided. Regions in thedosing system which urea enters only temporarily must be avoided sincethere is the danger that the aqueous urea solution will dry, the ureawill form crystals and clog the air channels or urea channels.

Here the tendency to clogging as a result of crystal formation by ureais disadvantageous. These crystals can be dissolved again by means ofliquid urea. But at least temporary clogging of the system cannot beavoided.

Commercial vehicles generally have a compressed air system for thebraking system and some additional consumers. The air pressure of thesystems is generally above 10 bar. In the known systems the compressedair of these compressed air systems of commercial vehicles is likewiseused for atomization or injection of the urea by means of the knowndosing systems. But the disadvantage is that the continuous airconsumption of the dosing system causes higher fuel consumption by theengine. It is likewise disadvantageous that the air supply must bematched to the additional consumers in the form of the urea dosingsystem. Here it is especially disadvantageous that compressors withincreased performance often become necessary.

Preferably the air pressure of the compressed air supply is monitoredand controlled according to requirements in the dosing system as claimedin the invention for injection of a urea solution into the exhaust gasflow. In the method for controlling the injection of a urea solution bymeans of compressed air into the exhaust gas flow of an internalcombustion engine for selective catalytic reduction, it is especiallyadvantageous that the amount of compressed air which is supplied foratomization of the urea solution is controlled at each operating pointdepending on the operating parameters exhaust gas temperature andexhaust gas flow and is reduced to the minimum amount of air which isrequired at the time so that the droplet quality of the injected ureasolution is sufficient for the action of the catalytic converter.

In the dosing system as claimed in the invention and the method forcontrolling the injection of the urea solution the compressed air issupplied controlled via a corresponding control valve. The suppliedamount of air is reduced at each operating point to such an extent thatthe droplet quality is still sufficient for the action of the catalyticconverter. This takes place by adapting the amount of compressed air ateach operating point of the engine depending on the operatingparameters: As operating parameters especially the exhaust gastemperature and/or the exhaust gas mass flow are detected and suppliedto the control of the amount of air, i.e. that the amount of air istracked depending on the current engine operating points.

A reduction in the amount of air in the nozzle means a deterioration ofthe droplet quality, i.e. larger droplet diameter. The minimallyrequired droplet quality is dependent on the efficiency of the catalyticconverter required at the respective operating point. The amount ofcompressed air is reduced to the required minimum according to therespective requirement. Preferably the air valve is a proportionalcontrol valve. By using a proportional control valve it is possible toexactly control the amount of air of the compressed air supply, i.e. theamount of air which is supplied for injection of the urea solution intothe exhaust gas flow. Preferably the sensor which is located between theair valve and the nozzle is a pressure sensor by means of which thepressure in the compressed air system downstream of the air valve ismonitored.

In one especially preferred embodiment the dosing system receives asignal of the exhaust gas mass flow from the engine control. The exhaustgas mass flow is computed by the engine control device from the intakenair mass flow and the fuel mass flow and is made available as a signalof the exhaust gas mass flow. Alternatively the dosing system has asensor for measuring the exhaust gas mass flow. Preferably the dosingsystem alternatively or cumulatively has a sensor for measuring theexhaust gas temperature.

From the exhaust gas mass flow signal and/or the exhaust gas temperatureit is possible to detect the operating parameters exhaust gastemperature and/or the exhaust gas mass flow which are dependent on therespective engine operating point and to evaluate them via correspondingcontrol electronics of the dosing system and to control the pressureand/or amount of air and/or valve opening times of the compressed airsupply depending on the measured operating parameters.

The variables for matching the dosing of the amount of air areespecially the following:

-   -   exhaust gas temperature    -   exhaust gas mass flow    -   urea mass flow    -   required catalytic converter efficiency    -   catalytic converter size    -   treatment distance between urea injection and catalytic        converter

It is thus possible with the dosing system as claimed in the inventionto optimize the amount of air at any individual operating pointdepending on the respective boundary conditions.

In one especially preferred embodiment the compressed air supply has athrottle valve. The arrangement of a throttle valve makes it possible toreduce the air pressure accordingly in the compressed air system beforefeed to the nozzle.

In one especially preferred embodiment the dosing system has a dosingpump for delivery of the urea solution. In particular this dosing pumpcan be a controllable dosing pump with respect to the delivered massflow of urea solution so that the delivery amount of urea solution canbe matched to the respective operating state by corresponding triggeringof the dosing pump.

Preferably there is a connecting line between the urea line and a lineof the compressed air supply, the connecting line having a nonreturnvalve. In order to completely interrupt the air supply in dosing pauses,it is necessary to remove the urea from the hot regions in order toavoid formation of deposits. Otherwise the urea would decompose at hightemperatures and lead to deposits and thus to clogging. The arrangementof a compressed air line, i.e. a connecting line between a urea line anda line of the compressed air supply, can prevent these deposits by theurea line being blown clear by means of compressed air in dosing pauses.A nonreturn valve is inserted into this connecting line and its openingpressure is above the air pressure which is established during dosingdownstream of the air valve.

In dosing operation this nonreturn valve is closed since the pressure inthe compressed air line is below the opening pressure of the nonreturnvalve. In order to blow the urea line clear with compressed air, thedelivery of urea by the dosing pump is shut off and the air valve isbriefly opened to such an extent that the pressure rises above theopening pressure of the nonreturn valve. Following the throttle in thecompressed air line a pressure drop occurs in the dosing line and thecompressed air drives the urea into the exhaust gas system. The line isthus blown clear. After a brief air blast the urea is blown out of thedosing nozzle and the air supply can be completely shut off.

Preferably the dosing system has a compressed air compressor. Thiscompressed air compressor makes it possible to make available thecompressed air which is delivered for the dosing system if there is nocompressed air supply or insufficient compressed air supply in theinstallation vicinity of the dosing system.

Preferably the dosing system has a control device by means of which theair valve and/or throttle valve and/or a dosing pump and/or a compressedair compressor can be controlled depending on the measured values whichhave been detected by the sensor or the sensors.

Optimization of the operation of the dosing system, i.e. airoptimization, can be implemented in an especially advantageous manner bythe arrangement of this control device which controls one or morecomponents of the dosing system depending on the sensor measured valves,i.e. depending on the current operating parameters. By means of thiscontrol device it is thus possible to optimally adapt the deliveryamount of urea solution and the delivery amount of air to the currentoperating parameters of the internal combustion engine and of thecatalytic converter for selective catalytic reduction and thus tocontrol them.

Preferably the dosing system has a urea solution tank. Because thedosing system itself has a urea solution tank, it is possible toretrofit the dosing system in corresponding environments in which thereis not already a urea solution tank. In one preferred embodiment thedosing system has a binary nozzle. Especially preferably the binarynozzle is an outer mixing nozzle.

The method as claimed in the invention for control of the injection of aurea solution by means of compressed air in the exhaust gas flow of aninternal combustion engine for selective catalytic reduction ispreferably configured such that when the injection of urea solution isinterrupted or ended the urea solution is removed from the lines whichcarry the urea solution by means of compressed air.

The method is therefore preferably configured such that termination orinterruption of the delivery of urea solution takes place in time priorto termination or interruption of the compressed air delivery and thecompressed air after interruption or termination of the delivery of ureasolution is used to clean the parts which carry urea solution by meansof compressed air. In this way the urea is removed especially from thehot regions of the dosing system. Otherwise the urea would decompose athigh temperatures and deposits would form and could lead to clogging.

In order to blow the urea line clear with compressed air, urea deliveryis shut off by the dosing pump and the air control valve is brieflyopened such that the pressure rises over the opening pressure of anonreturn valve in a connecting line between the urea line andcompressed air line. As a result a pressure drop occurs in the dosingline so that the compressed air drives the urea into the exhaust gassystem and thus the urea-carrying line is blown clear. After a brief airblast the urea is blown out of the dosing nozzle and the air supply canlikewise be completely shut off.

Interruption or termination of the injection of urea solution can thustake place by shutting off the dosing pump. Before turning on the dosingagain, it is useful to first set the compressed air to a value which isabove the normal dosing air supply in order to cool the nozzle beforethe urea enters it.

Blowing the urea out of the lines is likewise advantageous when theentire system is turned off. Urea freezes at temperatures below −11°Celsius. In doing so the urea water solution expands by roughly 10%.This leads to a frost pressure by which components could be destroyed.Therefore it is necessary to blow the urea out of the nozzle before thesystem is completely shut off. This can take place especially by theentire system being cleaned by means of compressed air after completionof urea delivery, i.e. by the urea being blown out of the system bymeans of compressed air.

Preferably triggering of at least one dosing pump and/or at least onecompressed air compressor and/or at least one air control valve takesplace depending on the operating parameters exhaust gas temperature andexhaust gas mass flow in the method as claimed in the invention forcontrolling the injection of the urea solution. For this purpose, bymeans of a corresponding control device the differently acquiredoperating parameters can be evaluated so that the components can beexactly triggered.

The figures show a schematic of a dosing system for injection of a ureasolution into the exhaust gas flow of an internal combustion engine andone exemplary embodiment of the component carrier as claimed in theinvention; they are explained below.

FIG. 1 shows a diagram of the arrangement of one embodiment of a dosingsystem;

FIG. 2 shows one embodiment of a component carrier as claimed in theinvention; and

FIG. 3 shows another embodiment of the component carrier of theinvention.

In the figures identical components and assemblies are labeled withidentical reference numbers. FIG. 1 schematically shows a urea dosingsystem. FIG. 2 shows one embodiment of a component carrier as claimed inthe invention in a top view (top) and a side view turned by 90°(bottom). FIG. 3 shows another embodiment of the component carrier ofthe invention in a cross-sectional top view.

Urea is sucked out of a tank 1 via an intake line 2 by the dosing pump3. The dosing pump 3 is for example a membrane pump or a piston pumpwhich with each stroke delivers a defined amount of urea solution andthus uniformly doses it. The urea is routed to a binary nozzle 5 via apressure line 4. The binary nozzle 5 is preferably an outer mixingnozzle in which an air jet atomizes the urea.

Compressed air is routed from a compressed air tank 6 to a proportionalair valve 7. The proportional air valve 7 sets the pressure flow to avalue dictated by the electronics 12. Input quantities for computingthis value by means of the electronic control unit 12 are engine datasuch as the exhaust gas mass flow which are transferred from the engineelectronics. Furthermore the exhaust gas temperature and the pressure ofthe compressed air upstream of the binary nozzle 5 [sic]. The pressureupstream of the binary nozzle 5 is a measurement of the volumetric airflow which has passed. The air is routed via a compressed air line and anonreturn valve 8 to the binary nozzle 5. The urea is atomized in thebinary nozzle 5 by the compressed air and supplied to the exhaust gasflow 9.

To detect the operating parameters exhaust gas flow, air pressure andexhaust gas temperature, there are a sensor 11 for detecting the exhaustgas mass flow, a pressure sensor 16 for detecting the pressure of thecompressed air upstream of the binary nozzle 5, and a temperature sensor17 for detecting the exhaust gas temperature in the exhaust gas flow 9.In one alternative which is not shown the exhaust gas mass flow signalis made available by the engine control.

The measured values of the sensors 11, 16, 17 are supplied to thecontrol unit 12. In the control unit 12 the detected sensor data andengine data are evaluated and triggering of the proportional air valve 7and dosing pump 3 takes place depending on the instantaneous operatingdata. The tip of the binary nozzle 5 is located in the exhaust gas flow9. The urea is routed to the SCR catalytic converter 10 via the exhaustgas line. In doing so a large part of the liquid droplets vaporizes. Theurea is converted into ammonia. In the catalytic converter 10 itself thenitrogen oxide emission of the engine is reduced with the ammonia.

The nonreturn valve 8 in the pressure line between the proportional airvalve 7 and binary nozzle 5 prevents the urea from being forced into thecompressed air line in possible clogs of the nozzle 5.

The compressed air line downstream of the proportional air valve 7 isconnected with the urea line 4 via a spring-loaded nonreturn valve 14 tothe line 13. Furthermore a flow throttle 15 is installed in thecompressed air line downstream of the proportional compressed air valve7 and downstream of the branch of the line 13. In this way it is easilypossible without additional actively actuated components to expel theurea from the pressure line and the nozzle using compressed air in orderto remove the urea from hot regions in the dosing pauses in order toprevent the urea from decomposing at high temperatures and formingdeposits.

Operation of the flow throttle 15 in the simplest case can be assumed bythe line itself if it is long enough. During dosing operation thepressure in the line from the throttle 15 is below the opening pressureof the spring-loaded nonreturn valve 14. The compressed air flowsthrough the nozzle 5. In this case the charged urea is atomized. If withthe dosing pump 3 turned off the pressure downstream of the proportionalpressure valve 7 is raised to a value above the opening pressure of thenonreturn valve 14, air flows into the pressure line 4 of the urea. Theurea in the line 4 and nozzle 5 is expelled. With this the region of thenozzle 5 after the engine is shut off is free of urea and thus resistantto freezing. Deposits cannot form in engine operation at high exhaustgas temperatures without dosing.

The pump 3, the proportional air valve 7 and the nonreturn valve 14 ofthe dosing system as shown in FIG. 1 are arranged on the componentcarrier 20 as shown in FIG. 2. The component carrier 20 integrates onthe one hand ports for the urea line 2 and the compressed air line 6, onthe other hand the ports 51, 52 to the nozzle 5, and within thecomponent carrier 20 the corresponding lines themselves. Via the port 51the heated urea solution delivered by the pump 3 is fed to the nozzle 5.Compressed air is fed to the nozzle 5 via the port 52.

Between the pressure side of the pump 3 and the compressed air supplythere is the spring-loaded nonreturn valve 14.

The component carrier 20 is formed by a solid plastic plate which iscompletely jacketed by a heat-conducing aluminum sheet. Along itslengthwise edges the plate has recesses 21, 22. The heat-conductivealuminum jacketing completely surrounds the component carrier 20including the recesses 21, 22. Coolant hoses 31, 32 of the internalcombustion engine are clipped into these recesses 21, 22. The componentcarrier 20 thus forms a heat sink within the coolant circuit of theinternal combustion engine. The components, i.e. the pump 3, the valves7, 14 and the port regions 51, 52 of the dosing system which are locatedon the component carrier 20 are heated by way of the heat which has beentransferred on this path from the coolant hoses 31, 32 via the contactregions 21, 22 to the component carrier 20.

Alternatively, as illustrated in FIG. 3, a component carrier 30 isformed by a solid base plate including a plurality of integrated innerflow channels 31. The base plate may be made of a metal, alloy, orplastic material having good heat conducting properties. The flowchannels 31 may be connected to the cooling circuit of the internalcombustion engine via an inlet port 32 and an outlet port 33. A fluidhaving an elevated temperature, such as hot engine coolant may flow fromthe inlet port 32 to the outlet port 33 by passing thorough the innerflow channels 31. The inner flow channels 31 are preferably designedsuch that heat from the coolant is transferred to the component carrier30. By heating the component carrier 30, the components mounted on thecomponent carrier 30, including the pump 3, the proportional air valve7, and the nonreturn valve 14 of the dosing system as shown in FIG. 1,will be heated through heat transfer by contact as well. Furthermore,the into the component carrier 30 integrated ports for the urea solutionline 2 and the compressed air line 6, the ports 51, 52 to the binarynozzle 5, as well as the corresponding connecting lines within thecomponent carrier 30 will also be heated by heat transferred from thecomponent carrier 30. The component carrier 30 thus forms a heat sinkwithin the coolant circuit of the internal combustion engine.

In accordance with a preferred embodiment of the invention, the innerflow channels 31 may be arranged in parallel. Other configurations maybe possible. The inner flow channels 31 may be in accordance withpreferred embodiments of the invention positioned at the top, the bottomor on either side of the component carrier 30.

By integrating the inner flow channels 31 of the component carrier 30into the cooling circuit of the internal combustion engine, allcomponents mounted on the component carrier 30 will be heatedautomatically and evenly through heat transfer by contact. No heatconducting jacket or separate heating elements are needed in accordancewith this embodiment of the invention. This simplifies maintenanceprocedures by making the components mounted on the component carrier 30easier accessible.

The arrangement of the component carrier 20 or 30 in accordance withpreferred embodiments of the invention reduces the mounting effort forthe dosing system. Various ports and lines are eliminated since they areintegrated into the component carrier 20 or 30. At the same time thesystem becomes more reliable due to fewer possible leak sites such ashose connections and hose ports. Forces would act on these hoseconnections and hose ports in a discrete structure of the system bydifferent vibrations/movement of the components to one another. Thesevibrations/movements of the components to one another are howeverprevented by the arrangement of the components on the component carrier.

The integration of the nonreturn valve 14 into the plate of thecomponent carrier 20 or 30 takes place in a position in which the springof the nonreturn valve 14 is continuously flushed with fresh urea duringdosing. After shutting off the dosing and the subsequent ventilation bythe nonreturn valve 14 the spring which is already wetted with urea can“set up/stick” (for example overnight) by the urea crystallizing out.This flushing by the special positioning of the nonreturn valve 14dissolves the dried urea again in the next dosing and transports it awayto the nozzle 5. Thus the nonreturn valve 14 can be used again after ashort dosing time.

Simple heating of the components and their connections among one anothertakes place. In accordance with an advantageous embodiment of theinvention, the component carrier 20 on the sides is made such that hoses31, 32 can be inserted into a round groove 21, 22. These hoses 31, 32are supplied with coolant from the vehicle. The hoses 31, 32 could bepositively forced into the grooves 21, 22 by a cover sheet/housing andthe components of the dosing system are protected from the outsideagainst dirt and the action of a force.

In accordance with a further advantageous embodiment of the invention,the component carrier 30 is integrated into the cooling circuit of theinternal combustion engine just like a radiator. The component carrier30 includes a plurality of inner flow channels 31 through which the hotcoolant flows from an inlet port 32 to an outlet port 33. The inlet port32 and the outlet port 33 are connected with the cooling circuit of theinternal combustion engine.

Accordingly, the component carrier 20 or 30 heats all the components,which include the pump 3, the proportional air valve 7 and the nonreturnvalve 14, the urea solution line 2, the compressed air line 6, and thebinary nozzle 5, located on it and the connecting ports for the ureasolution line 2 and the compressed air line 6, as well as the ports 51,52 to the binary nozzle 5. At the same time however excess exhaust heatof the dosing pump 3 is released to the component carrier 20. For thecomponent proportional valve 14 icing by humid air as a result ofpressure relief can no longer arise either.

While at least one exemplary embodiment has been presented in theforegoing summary and detailed description, it should be appreciatedthat a vast number of variations exist. It should also be appreciatedthat the exemplary embodiment or exemplary embodiments are onlyexamples, and are not intended to limit the scope, applicability, orconfiguration in any way. Rather, the foregoing summary and detaileddescription will provide those skilled in the art with a convenient roadmap for implementing at least one exemplary embodiment, it beingunderstood that various changes may be made in the function andarrangement of elements described in an exemplary embodiment withoutdeparting from the scope as set forth in the appended claims and theirlegal equivalents.

The invention claimed is:
 1. A component carrier of a dosing systemincluding a plurality of components for injecting a urea solution intothe exhaust gas flow of an internal combustion engine including acoolant circuit for selective catalytic reduction, comprising: a baseplate forming the component carrier; a plurality of inner flow channelsintegrated into the base plate; and an inlet port and an outlet portconnecting the inner flow channels with the coolant circuit of theinternal combustion engine; wherein the component carrier is heated byflowing a fluid having an elevated temperature and circulating in thecoolant circuit from the inlet port to the outlet port passing throughthe inner flow channels and transferring the heat from the fluid to thecomponent carrier; and wherein the components of the dosing systemmounted on the component carrier and in thermal contact with thecomponent carrier are heated through heat transfer from the heatedcomponent carrier by contact; wherein a compressed air line and an airvalve are mounted on the component carrier and in thermal contact withthe component carrier and are heated through heat transfer from theheated component carrier by contact.
 2. The component carrier of claim1, wherein the components of the dosing system mounted on the componentcarrier further include a pump, a nonreturn valve, a urea solution line,at least one nozzle, and ports to the urea solution line.
 3. Thecomponent carrier of claim 1, wherein the component carrier forms a heatsink within the coolant circuit of the internal combustion engine. 4.The component carrier of claim 1, wherein the base plate is made of ametal, alloy, or plastic material having good heat conductingproperties.
 5. The component carrier of claim 1, wherein the base plateis a solid plate.
 6. The component carrier of claim 1, wherein the fluidis engine coolant.
 7. The component carrier of claim 1, wherein theinner flow channels are designed such that heat from the fluid istransferred to the component carrier.
 8. The component carrier of claim1, wherein the inner flow channels are arranged in parallel.
 9. Thecomponent carrier of claim 1, wherein the inner flow channels arepositioned at the top, the bottom or on either side of the componentcarrier.
 10. The component carrier of claim 1, wherein the componentsmounted on the component carrier are heated automatically through heattransfer by contact.
 11. The component carrier of claim 1, wherein thedosing system is connected to a urea tank from which urea solution canbe taken, and wherein the dosing system is further connected to acompressed air supply.
 12. The component carrier of claim 11, whereinthe dosing system includes a pump for delivering the urea solution andat least one nozzle through which the urea solution is injected into anexhaust gas flow of the internal combustion engine by means ofcompressed air.
 13. The component carrier of claim 11, wherein thecomponent carrier has mounting elements of a vibration-damping material,and wherein the mounting elements are used to connect the componentcarrier with the urea tank.
 14. The component carrier of claim 11,wherein the components of the dosing system are pre-assembled to thecomponent carrier prior to the installation of the component carrier inthe urea tank.
 15. A dosing system for injecting a urea solution intothe exhaust gas flow of an internal combustion engine including acoolant circuit for selective catalytic reduction, the dosing systemcomprising: a urea solution line that connects the dosing system with aurea tank; a compressed air line that connects the dosing system to acompressed air supply; a pump for retrieving the urea solution from theurea tank; at least one nozzle through which the urea solution can beinjected into the exhaust gas flow utilizing compressed air from thecompressed air supply; an air valve positioned in the compressed airline; a nonreturn valve positioned downstream of the pump; and acomponent carrier including a plurality of inner flow channels and aninlet port and an outlet port connecting the inner flow channels withthe coolant circuit of the internal combustion engine; wherein the ureasolution line, the compressed air line, the pump, the at least onenozzle, the air valve and the nonreturn valve are mounted on thecomponent carrier and in thermal contact with the component carrier. 16.The dosing system of claim 15, wherein the component carrier is heatedby flowing a fluid having an elevated temperature and circulating in thecoolant circuit from the inlet port to the outlet port passing throughthe inner flow channels and transferring the heat from the fluid to thecomponent carrier.
 17. The dosing system of claim 15, wherein the ureasolution line, the compressed air line, the pump, the at least onenozzle, the air valve and the nonreturn valve are heated through heattransfer from the heated component carrier by contact.
 18. The dosingsystem of claim 15, wherein the amount of compressed air, which issupplied for atomization of the urea solution, is controlled at eachoperating point depending on the operating parameters exhaust gastemperature and exhaust gas flow and is reduced to the minimum amount ofair which is required at the time so that the droplet quality of theinjected urea solution is sufficient for the action of the catalyticconverter.
 19. The dosing system of claim 15, wherein the air valve is aproportional control valve enabling exact control of the amount of airthat is supplied for injection of the urea solution into the exhaust gasflow.
 20. A method for controlling the injection of urea solution intothe exhaust gas flow of an internal combustion engine including acoolant circuit for selective catalytic reduction, the method comprisingthe steps of: connecting a component carrier including a plurality ofinner flow channels and an inlet port and an outlet port connecting theinner flow channels with the coolant circuit of the internal combustionengine; mounting a plurality of components of a dosing system on thecomponent carrier and in contact with the component carrier, wherein thecomponents of the dosing system include an urea solution line, acompressed air line, a pump, at least one nozzle, an air valve and anonreturn valve; heating the component carrier by flowing a fluid, whichhas an elevated temperature and circulates in the coolant circuit, fromthe inlet port to the outlet port thereby passing through the inner flowchannels and transferring the heat from the fluid to the componentcarrier; heating the plurality of components of the dosing systemthrough heat transfer from the heated component carrier by contact; andforming with the component carrier a heat sink within the coolantcircuit of the internal combustion engine.